Hello everyone and welcome to another Stellaris dev diary. Today's dev diary is about some changes coming to ground combat and armies in the 2.0 'Cherryh' update. This will be the last dev diary before we take a break for the holidays, so there will be no diaries in the next week or the week after that. Stellaris dev diaries return on Thursday January 11th, 2018.
Defense Armies and Fortresses
Constructing Defense Armies have always been largely a meaningless exercise in Stellaris. While they are useful for reducing Unrest and occasionally might be able to beat off an unprepared attacker, the fact that a planet is capped on how many armies can be defending it while the attacker is *not* capped on how many armies are attacking, coupled with the general weakness of defense armies, means that defending a planet against a ground invasion is generally an exercise in futility and will at most delay an attacker by a few weeks. However, if we solved this by just making defense armies a lot stronger or capping the number of attacking units, the result would turn every invasion of a backwater colony into a big affair - something that is not particularly desirable when a war can involve several different actors with hundreds of planets between them.
For this reason, we have decided to rework Defense Armies into something that is actually useful, but requires a significant investment of resources to muster more than a token defense. Instead of being directly buildable by the empire, defense armies are created from certain buildings. The capital building will produce defense armies depending on its level, as will some other planetary uniques like Military Academy. If you want a planet to be well defended, however, you will need to construct Fortress building on its tiles. Fortresses require a pop to work them, do not produce any other resources than a small amount of Unity, but provide a significant amount of defense armies to protect the planet. Armies spawned by Fortresses are also impervious to orbital bombardment, and will not be able to be killed without first ruining the building itself. The armies generated by a building have their species and type set by the pop working it, so a Very Strong Battle Thrall will produce several powerful defense armies if placed on a Fortress, and special pops like Droids will produce their own variants like Robotic Defense Armies rather than the normal ones. Fortified worlds will also be able to be fit with an FTL inhibitor (the exact way they get them is not yet determined) that prevents enemy fleets from leaving the system unless the world is captured, which allows for the creation of Fortress Worlds to protect strategically important systems.
(Building icon is a placeholder)
One more important change related to Defense Armies is a change to Unrest: Armies on planets no longer reduce Unrest directly. Instead, to handle a planet with high Unrest, you will need to construct Fortress-style buildings or take other measures (such as using Edicts) to reduce the planetary Unrest. This means you cannot simply capture a planet and then spam a dozen defense armies to immediately zero out the Unrest. As part of this, we will be balancing certain events and effect to ensure newly captured worlds do not instantly defect back to their former owner.
Finally, as part of all these changes Defense Armies have received a general buff and there are several new technologies that unlock additional tiers of forts and various improvements to Defense Armies' combat ability, meaning that they will grow stronger alongside the invention of new, more powerful assault armies.
Assault Army Management
A major aim of our changes to armies is to reduce the amount of unnecessary micromanagement of armies. For this reason, and to make Assault Armies' role more explicit, we have decided to change Assault Armies to always be based in space. Whenever not directly engaged in an invasion, Assault Armies will now always automatically embark onto their transports, ready to be used to invade another world. We also aim to fix the minor but immersion-breaking bug where transport fleets are giving endlessly increasing sequential names whenever they land and embark again.
Combat Width, Retreating and Collateral Damage
Another change to ground combat is the introduction of new mechanics in the form of Combat Width. Combat Width is determined by the size of the planet, and decides how many armies can be taking and receiving damage at the same time: For example, if 20 assault armies invade a world held by 10 defense armies with a combat width of 10, all 10 defense armies will be immediately engaged in battle while only half the assault armies will be able to deal and receive damage, with additional assault armies joining the fray as the armies in front of them are destroyed. This means that it is no longer possible to take a well defended world without losses by simply throwing a hundred clone armies at it: If you wish to minimize losses (and thus War Exhaustion), you will need to invest in expensive, high-maintenance elite armies.
(Interface not final)
We've also added the concept of Collateral Damage: As armies fight on the planet, civilians and civilian infrastructure is caught in the fighting. Each time an army deals damage in battle, it will inflict a random amount of Collateral Damage, which increases Planetary Damage similar to Orbital Bombardment (see below) and can lead to the death of Pops and the destruction of buildings and tiles. Some armies will deal more Collateral Damage than others: For example, Xenomorph armies are highly destructive and cost-efficient, but will wreak immense havoc on the planet, potentially leaving it in ruins in the process of capturing it for your empire.
While working on combat mechanics we also took the time to change the way Morale Damage works, making it something that is suffered by both sides (instead of just the loser) and making the effects of it more gradual, so that armies suffer a drop in combat efficiency once they are <50% morale, and then another, sharper drop when they are broken (0% morale). This should make certain armies, such as Psi Armies, highly effective against low-morale opponents like Slave Armies, but less effective against an unfeeling army of Droids. Finally, we've also tweaked the damage-dealing algorithm so that damage is less evenly spread among combatants, making it so that even an outnumbered force can destroy regiments and inflict war exhaustion on the enemy.
Finally, we have made some changes to retreats. When an attacker retreats from a ground combat, there is now a significant chance that each retreating regiment is destroyed while attempting to return to space, making retreat a risky endeavour and eliminating the tactic of simply send in the same army again and again in wave attacks, instead making retreats something you do in order to preserve at least some of your army in a poorly chosen engagement.
Orbital Bombardment Changes
Finally, again in the interest of reducing the micromanagement needed during war, we've changed the way orbital bombardment works. Fortifications have been entirely cut from planets, so that there is no need to bombard lightly defended worlds before going in with the ground troops. Instead, we have added a requirement that planets cannot be invaded if there is a hostile Starbase in the system, so that transports cannot snipe worlds that are protected by defensive installations present in the same system. Orbital Bombardment, instead of being something you have to manage and wait for in every single planetary engagement, is now something you do to soften up a particularly well defended target, or simply to wreak havoc on the enemy's planet and drive up their War Exhaustion.
As a planet is bombarded, the fleet will deal Planetary Damage, ruining buildings and killing Pops. Bombarding fleets will also do damage to armies present on the planet (unless those armies are protected by a Fortress), and over a long enough time can decimate a defending force, though doing so will likely cause heavy damage to the planet and may delay the attacker long enough that the owner of the planet has time to build up their forces or inflict enough war exhaustion to force a peace. The rate at which the planet is damaged can also be slowed with the construction of buildings such as Planetary Defense Shield, further dragging out the process.
As part of these changes, we've consolidated the Bombardment Stances into the following:
Attachments
Finally, on the topic of attachments, we have decided to cut them entirely from the game. We discussed a variety of ways to improve the way you assign them, but ultimately decided that we already have so many types of armies and not nearly enough combat mechanics to justify a significant investment of UI time that could go towards something like the Fleet Manager instead. The technologies that previously unlocked attachments will be changed to give other effects, such as direct buffs to certain army types.
That's all for today! As I said, we're now going on hiatus, so I'll see you again on January 11th with a dev diary about... well, that's a secret, actually. You'll just have to wait and see!
Defense Armies and Fortresses
Constructing Defense Armies have always been largely a meaningless exercise in Stellaris. While they are useful for reducing Unrest and occasionally might be able to beat off an unprepared attacker, the fact that a planet is capped on how many armies can be defending it while the attacker is *not* capped on how many armies are attacking, coupled with the general weakness of defense armies, means that defending a planet against a ground invasion is generally an exercise in futility and will at most delay an attacker by a few weeks. However, if we solved this by just making defense armies a lot stronger or capping the number of attacking units, the result would turn every invasion of a backwater colony into a big affair - something that is not particularly desirable when a war can involve several different actors with hundreds of planets between them.
For this reason, we have decided to rework Defense Armies into something that is actually useful, but requires a significant investment of resources to muster more than a token defense. Instead of being directly buildable by the empire, defense armies are created from certain buildings. The capital building will produce defense armies depending on its level, as will some other planetary uniques like Military Academy. If you want a planet to be well defended, however, you will need to construct Fortress building on its tiles. Fortresses require a pop to work them, do not produce any other resources than a small amount of Unity, but provide a significant amount of defense armies to protect the planet. Armies spawned by Fortresses are also impervious to orbital bombardment, and will not be able to be killed without first ruining the building itself. The armies generated by a building have their species and type set by the pop working it, so a Very Strong Battle Thrall will produce several powerful defense armies if placed on a Fortress, and special pops like Droids will produce their own variants like Robotic Defense Armies rather than the normal ones. Fortified worlds will also be able to be fit with an FTL inhibitor (the exact way they get them is not yet determined) that prevents enemy fleets from leaving the system unless the world is captured, which allows for the creation of Fortress Worlds to protect strategically important systems.
(Building icon is a placeholder)
One more important change related to Defense Armies is a change to Unrest: Armies on planets no longer reduce Unrest directly. Instead, to handle a planet with high Unrest, you will need to construct Fortress-style buildings or take other measures (such as using Edicts) to reduce the planetary Unrest. This means you cannot simply capture a planet and then spam a dozen defense armies to immediately zero out the Unrest. As part of this, we will be balancing certain events and effect to ensure newly captured worlds do not instantly defect back to their former owner.
Finally, as part of all these changes Defense Armies have received a general buff and there are several new technologies that unlock additional tiers of forts and various improvements to Defense Armies' combat ability, meaning that they will grow stronger alongside the invention of new, more powerful assault armies.
Assault Army Management
A major aim of our changes to armies is to reduce the amount of unnecessary micromanagement of armies. For this reason, and to make Assault Armies' role more explicit, we have decided to change Assault Armies to always be based in space. Whenever not directly engaged in an invasion, Assault Armies will now always automatically embark onto their transports, ready to be used to invade another world. We also aim to fix the minor but immersion-breaking bug where transport fleets are giving endlessly increasing sequential names whenever they land and embark again.
Combat Width, Retreating and Collateral Damage
Another change to ground combat is the introduction of new mechanics in the form of Combat Width. Combat Width is determined by the size of the planet, and decides how many armies can be taking and receiving damage at the same time: For example, if 20 assault armies invade a world held by 10 defense armies with a combat width of 10, all 10 defense armies will be immediately engaged in battle while only half the assault armies will be able to deal and receive damage, with additional assault armies joining the fray as the armies in front of them are destroyed. This means that it is no longer possible to take a well defended world without losses by simply throwing a hundred clone armies at it: If you wish to minimize losses (and thus War Exhaustion), you will need to invest in expensive, high-maintenance elite armies.
(Interface not final)
We've also added the concept of Collateral Damage: As armies fight on the planet, civilians and civilian infrastructure is caught in the fighting. Each time an army deals damage in battle, it will inflict a random amount of Collateral Damage, which increases Planetary Damage similar to Orbital Bombardment (see below) and can lead to the death of Pops and the destruction of buildings and tiles. Some armies will deal more Collateral Damage than others: For example, Xenomorph armies are highly destructive and cost-efficient, but will wreak immense havoc on the planet, potentially leaving it in ruins in the process of capturing it for your empire.
While working on combat mechanics we also took the time to change the way Morale Damage works, making it something that is suffered by both sides (instead of just the loser) and making the effects of it more gradual, so that armies suffer a drop in combat efficiency once they are <50% morale, and then another, sharper drop when they are broken (0% morale). This should make certain armies, such as Psi Armies, highly effective against low-morale opponents like Slave Armies, but less effective against an unfeeling army of Droids. Finally, we've also tweaked the damage-dealing algorithm so that damage is less evenly spread among combatants, making it so that even an outnumbered force can destroy regiments and inflict war exhaustion on the enemy.
Finally, we have made some changes to retreats. When an attacker retreats from a ground combat, there is now a significant chance that each retreating regiment is destroyed while attempting to return to space, making retreat a risky endeavour and eliminating the tactic of simply send in the same army again and again in wave attacks, instead making retreats something you do in order to preserve at least some of your army in a poorly chosen engagement.
Orbital Bombardment Changes
Finally, again in the interest of reducing the micromanagement needed during war, we've changed the way orbital bombardment works. Fortifications have been entirely cut from planets, so that there is no need to bombard lightly defended worlds before going in with the ground troops. Instead, we have added a requirement that planets cannot be invaded if there is a hostile Starbase in the system, so that transports cannot snipe worlds that are protected by defensive installations present in the same system. Orbital Bombardment, instead of being something you have to manage and wait for in every single planetary engagement, is now something you do to soften up a particularly well defended target, or simply to wreak havoc on the enemy's planet and drive up their War Exhaustion.
As a planet is bombarded, the fleet will deal Planetary Damage, ruining buildings and killing Pops. Bombarding fleets will also do damage to armies present on the planet (unless those armies are protected by a Fortress), and over a long enough time can decimate a defending force, though doing so will likely cause heavy damage to the planet and may delay the attacker long enough that the owner of the planet has time to build up their forces or inflict enough war exhaustion to force a peace. The rate at which the planet is damaged can also be slowed with the construction of buildings such as Planetary Defense Shield, further dragging out the process.
As part of these changes, we've consolidated the Bombardment Stances into the following:
- Selective: Deals normal damage to armies/buildings and light damage to pops. Cannot kill the last 10 pops.
- Indiscriminate: Deals heavy damage to armies, buildings and pops. Cannot kill the last 5 pops.
- Armageddon: Deals massive damage to armies, buildings and pops. Can turn planets into depopulated Tomb Worlds with enough bombardment. Only available to certain empires such as Purifiers.
Attachments
Finally, on the topic of attachments, we have decided to cut them entirely from the game. We discussed a variety of ways to improve the way you assign them, but ultimately decided that we already have so many types of armies and not nearly enough combat mechanics to justify a significant investment of UI time that could go towards something like the Fleet Manager instead. The technologies that previously unlocked attachments will be changed to give other effects, such as direct buffs to certain army types.
That's all for today! As I said, we're now going on hiatus, so I'll see you again on January 11th with a dev diary about... well, that's a secret, actually. You'll just have to wait and see!
. Here's wishing you and the rest of the Stellaris team a very Merry Christmas and a Happy New Year 
